UE4 angle과 acos를 이용한 원형 회전 하기

// Sets default values
ARevolveCameraContorller::ARevolveCameraContorller()
{
     // Set this actor to call Tick() every frame.  You can turn this off to improve performance if you don't need it.
    PrimaryActorTick.bCanEverTick = true;
 
    RootComp = CreateDefaultSubobject<USceneComponent>(TEXT("Root"));
    RootComp->ComponentTags.Add("RollingBall");
 
    RootComponent = RootComp;
 
    RevolveCam = CreateDefaultSubobject<UCameraComponent>(TEXT("Revolve Cam"));    
    RevolveCam->SetRelativeLocation(FVector(0.0f, 0.0f, 150.0f));
    RevolveCam->SetRelativeRotation(FRotator(-10.0f, 180.0f, 0.0f).Quaternion());
    RevolveCam->AttachTo(RootComponent);
    
    RevolveRadious = 300.0f;
 
    CurrentRevolveAngle = 0.0f;
 
    RevolveAngleSpeed = 30.0f;
}
 
// Called when the game starts or when spawned
void ARevolveCameraContorller::BeginPlay()
{
    Super::BeginPlay();
}
 
// Called every frame
void ARevolveCameraContorller::Tick( float DeltaTime )
{
    Super::Tick( DeltaTime );
 
    CurrentRevolveAngle += (RevolveAngleSpeed * DeltaTime);
    
    if (CurrentRevolveAngle > 360.0f)
    {
        CurrentRevolveAngle = 0.0f;
    }
    
    FVector newPosition =  GetNewPosition(CurrentRevolveAngle, RevolveRadious);
    
    if (Cameratarget != nullptr)
    {
        FVector targetPos = Cameratarget->GetTransform().GetLocation();
        targetPos.Z = 0.0f;
        newPosition = targetPos + newPosition;
    }
 
    RootComponent->SetWorldLocation(newPosition);
    
    RevolveCam->SetRelativeRotation(FRotator(-10.0f, 180.0f + CurrentRevolveAngle, 0.0f).Quaternion());
}
 
FVector ARevolveCameraContorller::GetNewPosition(const float angle, const float radious)
{
    FVector Pos = FVector::ZeroVector;
 
    float CurrentAngle = 0.0f;
 
    if (angle < 180.0f)
    {
        CurrentAngle = angle;
    }
    else if (angle < 360.0f)
    {
        CurrentAngle = 360.0f - angle;
    }
 
 
    float acos = (90.0f - CurrentAngle) / 90.0f;
 
    Pos.X = acos;
 
    float x2 = acos * acos;
 
    
    if (angle < 180.0f)
    {
        Pos.Y = FMath::Sqrt(1 - x2);
    }
    else if (angle < 360.0f)
    {
        Pos.Y = - FMath::Sqrt(1 - x2);
    }
    
    //FString str = FString::Printf(TEXT("Angle : %.1f    / acos : %.1f    / PosX : %.1f    / PosY : %.1f    "), angle, acos , Pos.X, Pos.Y);
    //
    //GEngine->AddOnScreenDebugMessage(-1, 0.2f, FColor::Green, str);
 
 
    return Pos * radious;
}

*** aCos의 값은 0 <= angle <= π ( -1 <= value <= -1) 이다.